Clinical Manifestations

As previously shown, mild behavioral impairment (MBI), characterized by late-life emergent and persistant neuropsychiatric symptoms (NPS) with minimal impact on daily life, is associated with increased dementia risk. Z. Ismail et al. have proposed an informant-based checklist (MBI-C), a 34-item list, structured into 5 domains in accordance with ISTAART criteria, to quantify MBI. This study examines the MBI-C utility in Russian-speaking patients with mild cognitive impairment (MCI).

Eighty-six patients (age 71 [65;76] years, 70 female) with MCI (according to R. Petersen criteria) underwent a clinical, neuropsychological, and behavioral assessment in a specialized Alzheimer's disease department, with a 3-year follow-up. Montreal Cognitive Assessment (MoCA), Clinical Dementia Rating (CDR), and MBI-C scores were obtained at baseline and follow-up visits. MBI was diagnosed based on ISTAART criteria and with an MBI-C total score of >6. A diagnosis of dementia was based on ICD-10 criteria and CDR total score of >1. Statistical analysis included the Wilcoxon signed-rank test to evaluate differences between two time points, a two-way ANOVA was performed to evaluate the effect of the MBI-C total score over time on conversion to dementia.

Eighteen patients converted to dementia (16-AD, 2-bvFTD). Converters had significantly higher baseline MBI-C scores (8 [6;15.5]) compared to non-converters (4 [1;10], p = 0.002). Differences were also significant in all domains except affective dysregulation. Pairwise comparisons showed that the mean MBI-C scores in impulse dyscontrol (p = 0.03) and in total (p = 0.009) increased significantly in converters over time. A significant interaction between baseline MBI-C total score and clinical outcome was found (F(1,164) = 56.6, p <0.001) with a large effect size (ges=0.26). While time alone had no effect on MBI-C and conversion, patients with MCI and MBI showed significant MoCA decline (22.6 to 20.6, p = 0.007), unlike MCI-only patients (24.2 to 24.3).

The MBI-C shows strong utility in a Russian-speaking MCI population. It demonstrates relevance as a sensitive measure of behavioral symptoms that precede dementia. The strong association between baseline MBI-C scores and subsequent decline highlights its predictive power for the progression of neurodegenerative disorders, complementing routine cognitive measures.